1. Field of the Invention
This invention relates to a solid electrolytic capacitor, such as tantalum capacitor or aluminum capacitor, which comprises a capacitor element enclosed in a resin package.
2. Description of the Prior Art
A package-type solid electrolytic capacitor is known from Japanese Patent Application Laid-open No. 60-220922 for example. The capacitor disclosed in this Japanese document has such a structure, as shown in FIG. 15.
Specifically, the prior art capacitor comprises a capacitor element 11 which includes a capacitor chip 11a and an anode wire 11b partially projecting from the chip 1a. The chip may be a compacted mass of tantalum powder for example, in which case the anode wire 11b is also made of tantalum.
The capacitor also includes an anode lead 12 and a cathode lead 13. The anode lead 12 has an inner end 12a electrically connected, from below, to the anode wire 11b by welding for example. The cathode lead 13 has an inner end 13a held in contact with the underside of the chip 11a and electrically connected thereto by a solidified conductive paste 14 such as metal paste or electrically conductive resin paste.
The capacitor further includes a resin package 15 enclosing the capacitor element 11 together with part of the anode and cathode leads 12, 13. The respective leads 12, 13 are bent toward the underside of the resin package 15 for conveniently mounting to a surface of a circuit board (not shown).
According to the prior art arrangement described above, since the inner end 13a of the cathode lead 13 is attached to the underside of the chip 11a, the cathode lead is required to have an inclined bent portion 13b extending from the inner end. Thus, the overall length L' of the capacitor must be increased due to the presence of the inclined bent portion 13b. Further, since the dimension H1' below the chip 11a need be increased by an amount corresponding to the thickness of the cathode lead 13 plus the thickness of the conductive paste 14, the overall height H' of the capacitor must be correspondingly increased. As a result, there is a relatively high limitation in reducing the size and weight of the capacitor.
Further, with the prior art capacitor, the conductive paste 14 is substantially concealed by the inner end 13a of the cathode lead 13, thereby preventing the use of laser beam irradiation for solidification of the conductive paste 14. Instead, the capacitor element 11 as a whole need be heated for a prolonged period of time to solidify the conductive paste. As a result, the capacitor element 11 may be thermally damaged at the time of solidifying the conductive paste 14.
FIG. 16 shows another prior art package-type solid electrolytic capacitor. Again, this capacitor comprises a capacitor element 11 which includes a capacitor chip 11a and an anode wire 11b partially projecting from the chip 1a.
The capacitor also includes an anode lead 12' and a cathode lead 13'. The anode lead 12' has an inner end 12a electrically connected, from above, to the anode wire 11b' by welding. The cathode lead 13' has an inner end 13a' held in contact with the underside of the chip 11a' and electrically connected thereto by a solidified conductive paste 14'. Further, the cathode lead 13' has an inclined bent portion 13b' extending from the inner end 13a.
The capacitor further includes a resin package 15' enclosing the capacitor element 11' together with part of the anode and cathode leads 12', 13'. The-respective leads 12', 13' are bent toward the underside of the resin package 15' for conveniently mounting to a surface of a circuit board.
Obviously, due to the need for attaching the inner end 13' of the cathode lead 13' to the upper surface of the chip 11a' and for providing the inclined bent portion 13b', there is a relatively high limitation in reducing the overall length L" and height H" of the capacitor.